problem switch_audio command in slave mode and mpegpes output

Hi,
I am getting the following when using switch_audio slave command using a
dvb card for primary output:

switch_audio
==========================================================================
Opening audio decoder: [mp3lib] MPEG layer-2, layer-3
AUDIO: 48000 Hz, 2 ch, s16le, 256.0 kbit/16.67% (ratio: 32000->192000)
Selected audio codec: [mp3] afm: mp3lib (mp3lib MPEG layer-2, layer-3)
==========================================================================
Opening /dev/dvb/adapter0/audio0
DVB AUDIO DEVICE: Device or resource busy
Could not open/initialize audio device -> no sound.

I this problem known? 
Any ideas to solve this?
BR.
Halim